JP2006053220A - Member having antireflection part, molding die for the member and method of manufacturing the die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a member having an antireflection part reducing the effects of the incident angle of light, the curvature and area of the surface of the member, etc., and making the antireflection effect of the entire curved face uniform. <P>SOLUTION: At least a part of a virtual curved face 12 forming the member 10 has an antireflection part 11 composed of a minute cyclic recess-and-projection structure formed at a pitch not longer than the wavelength of light to be prevented from being reflected. The center lines of the recesses and projections 11a and 11b forming the antireflection part are made to almost coincide with the vector of the normal of the curved face 12 obtained through the calculation in which the antireflection part 11 is assumed not to be present. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a member in which an antireflection portion having a fine periodic concavo-convex structure is formed on a curved surface such as a lens surface, a molding die thereof, and a method of manufacturing the molding die, and in particular, uniform antireflection effect over the entire curved surface. A member having an antireflection part capable of effectively exhibiting the antireflection effect as a whole even when the surface of the member has a large curvature or a large area, its mold, and production of the mold Regarding the method.

Conventionally, in order to reduce reflected return light on the surface of an optical element such as a lens, it has been known to provide an antireflection portion having a fine concavo-convex structure called Sub-Wavelength-Structure (SWS) on the surface of the optical element. ing.

For example, in Japanese Patent Application Laid-Open No. 2003-43203, an inversion-shaped molding surface of a target optical element is formed on a molding die, and then a layer made of an etching rate gradient material is formed on the molding surface, and the gradient material layer is used as a mask. Etching to form a large number of fine irregularities on the molding surface, supplying a raw material to be an optical element on the molding surface, press molding, and further curing the raw material with ultraviolet rays or the like The optical element obtained by this, its shaping | molding die, and the manufacturing method of this optical element are proposed.
Japanese Patent Laying-Open No. 2003-43203 (see paragraph numbers 0012 to 0026 and FIG. 1)

  However, in the conventional SWS structure described above, as shown in FIG. 8, a large number of fine irregularities 111a and 111b are formed on a virtual curved surface (curved surface assuming that the SWS structure 111 does not exist) 112 of the optical element 100. All of them were configured to project in the vertical direction. For this reason, as shown in FIG. 9, as the light incident angle θ with respect to the concavo-convex portions 111a and 111b increases, the reflectance of the light increases, and as a result, when the light is incident from a direction other than the vertical direction, There is a problem in that the antireflection effect decreases as the distance from the central portion of 100 approaches the peripheral portion.

  As a result, in the above-described conventional technology, the antireflection effect is not uniform between the central portion and the peripheral portion of the optical element, and when the surface curvature of the optical element is small or large, the antireflection effect is generally improved. There was also a problem that it could not be used effectively.

  The present invention has been made in view of the above problems, and it is possible to reduce the influence of the light incident angle, the curvature and area of the surface of the member, and to make the antireflection effect uniform over the entire curved surface. It aims at providing the member which has, its shaping | molding die, and the manufacturing method of this shaping | molding die.

  In order to achieve the above object, a member having an antireflection portion according to the present invention is a fine material formed on at least a part of an actual or virtual curved surface forming a member with a pitch equal to or less than the wavelength of a light beam to be antireflection. An antireflection portion having a periodic concavo-convex structure is provided, and the center line of each concavo-convex portion forming the antireflection portion is made to substantially coincide with the normal vector of the curved surface when it is assumed that the antireflection portion does not exist. As a configuration.

  Preferably, a configuration in which the pitch of the concavo-convex portions forming the antireflection portion is 100 to 400 nm, a configuration in which the curved surface of the member is a spherical surface, an aspherical surface, or a free curved surface, or a configuration in which the member is an optical element. Good.

  In order to achieve the above object, a mold according to the present invention is a mold for manufacturing a member having the antireflection portion, and is at least a part of a real or virtual curved surface forming the mold surface. The curved surface when it is assumed that there is no fine periodic concavo-convex portion, and the center line of each of the concavo-convex portions forming the fine periodic concavo-convex portion has a fine periodic concavo-convex portion obtained by inverting the antireflection portion. The normal vector is substantially the same.

  Preferably, the pitch of the concave and convex portions forming the fine periodic concave and convex portions is 100 to 400 nm, the curved surface forming the mold surface is a spherical surface, an aspherical surface, or a free curved surface, or the mold is an optical element. It is set as the structure for manufacture of this.

  Furthermore, in order to achieve the above-mentioned object, the manufacturing method of the molding die according to the present invention includes the fine periodic concavo-convex portion or a microscopic surface obtained by inverting this on the curved surface of the molding die or the mold for producing the molding die. This is a procedure including a step of forming the periodic irregularities by anodizing.

  Preferably, the procedure includes a step of forming the fine periodic concavo-convex part or the fine periodic concavo-convex part obtained by inverting the fine periodic concavo-convex part by anodizing aluminum, and the purity of the aluminum is 99% or more. Alternatively, the surface roughness of the aluminum is 50 nm or less. More preferably, the aluminum film is formed on the mold or mold base and anodized, and the film thickness of the aluminum film formed on the mold or mold base is 2 μm or more. Further, the fine periodic concavo-convex portion formed by the anodic oxidation method or the fine periodic concavo-convex portion obtained by inverting this may be plated with Ni.

  According to the member having the antireflection portion according to the present invention, each of the concavo-convex portions forming the antireflection portion is directed toward the normal direction of the curved surface (the curved surface when it is assumed that there is no antireflection portion). Each of the protrusions and protrusions has an inclination corresponding to the curvature of the curved surface, which reduces the influence of the light incident angle, the curvature and area of the curved surface, and the center of the curved surface. The overall antireflection effect from the part to the peripheral part can be made uniform. Thereby, even when the curvature of the surface of the member is small or large, the antireflection effect can be effectively exhibited as a whole.

  Further, according to the molding die having the antireflection portion according to the present invention, the shape of the fine periodic unevenness portion is transferred to the molding material, so that the above-described member having the antireflection portion having the uniform antireflection effect can be manufactured at low cost and in large quantities. Can be manufactured.

  Furthermore, according to the method for manufacturing a mold having an antireflection portion according to the present invention, the fine periodic unevenness is formed by anodizing on the curved surface of the mold or the mold used for manufacturing the mold. The individual irregularities constituting the fine periodic irregularities can be directed in the direction of the normal vector of the curved surface, and in particular, even if the curved surface has a large area, the fine periodic irregularities are uniform. The part can be formed.

  Hereinafter, a member having an antireflection portion according to an embodiment of the present invention, a molding die thereof, and a manufacturing method of the molding die will be described with reference to the drawings. First, a member having an antireflection portion according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side view showing a member (optical element) having an antireflection portion according to this embodiment.

  In the figure, an optical element (a member having an antireflection portion) 10 is a biconvex lens, and has an antireflection portion 11 on one convex surface. The antireflection portion 11 is composed of a large number of fine periodic concavo-convex structures formed at a pitch equal to or less than the wavelength of the light beam to be antireflective, and the center lines of the individual concavo-convex portions 11a and 11b forming the antireflection portion 11 (see FIG. 1 is substantially matched with the normal vector of the virtual curved surface 12 (see the chain line in the enlarged view in FIG. 1) when it is assumed that the antireflection portion 11 does not exist.

  As described above, the center lines of the individual concavo-convex portions 11a and 11b are made to coincide with the normal vector of the virtual curved surface 12 when it is assumed that the antireflection portion 11 does not exist. The center lines pass through one point of the virtual curved surface 12 and are orthogonal to the tangent plane at that point. That is, each uneven | corrugated | grooved part 11a, 11b has faced the direction of about 90 degrees with respect to the virtual curved surface 12 which each contact | connects conceptually.

  It is desirable that each of the uneven portions 11a and 11b forming the antireflection portion 11 is oriented substantially at 90 ° with respect to the virtual curved surface 12 without variation. In consideration of the case where the concavo-convex shape of the film is not bent and is not completely restored after the peeling is completed, an error of about ± 5 ° is allowed. Moreover, the shape of the convex part 11b can be made into cone shapes, such as a cone, a quadrangular pyramid, and a triangular pyramid, for example, and if it is possible to obtain an antireflection effect, it can also be made into a bell-like shape other than these.

  Furthermore, in this embodiment, the pitch of the concavo-convex portions 11a and 11b forming the antireflection portion 11 is set to 100 to 400 nm below the visible light region. Thereby, the anti-reflective part 11 can permeate | transmit visible light reliably, and there exists a remarkable anti-reflective effect. In addition to this, the virtual curved surface 12 of the optical element 10 may normally be any of a spherical surface, an aspherical surface, and a free curved surface forming a lens surface.

  According to such an optical element 10 according to the present embodiment, the individual concavo-convex portions 11a and 11b that form the antireflection portion 11 face the normal direction of the virtual curved surface 12 that is in contact with each other. Of the concavo-convex portions 11a and 11b each have an inclination corresponding to the curvature of the virtual curved surface 12, which reduces the influence of the light incident angle θ (see FIGS. 8 and 9), the curvature and area of the virtual curved surface 12, and the like. The entire antireflection effect from the central part to the peripheral part of the virtual curved surface 12 can be made uniform. Thereby, even when the curvature of the lens surface of the optical element 10 is small or large, the antireflection effect can be effectively exhibited as a whole.

  In addition, although this embodiment mentioned above demonstrated the case of the optical element 10 which has the reflection preventing part 11, the member used as the object of this invention is limited to optical elements, such as a lens and an optical display part. Instead, for example, various parts or finished products other than the optical element that require antireflection, such as a frame for supporting the optical element, are targeted.

  Next, an embodiment of a mold for manufacturing a member having an antireflection portion according to the present invention will be described with reference to the drawings. The mold according to the present embodiment is a case where a biconvex lens is manufactured by cast molding of an ultraviolet curable resin, and each of the upper mold and the lower mold forms an antireflection portion on both lens surfaces of the biconvex lens. It is supposed to be.

  FIGS. 2A to 2E are explanatory views showing a manufacturing process of a Ni mold which is a mold (upper mold) according to the present embodiment. FIGS. 3A to 3E are explanatory views showing a manufacturing process of a glass mold which is a mold (lower mold) according to this embodiment.

  In FIG. 2 (e), an Ni (nickel) mold 30 which is an upper mold is for forming one lens surface and an antireflection portion of the optical element (biconvex lens), and a large number of mold surfaces are formed on the mold surface. A fine periodic uneven portion 31 is provided. The center line of each uneven portion forming the fine periodic uneven portion 31 is an imaginary curved surface when the fine periodic uneven portion 31 does not exist (the Ni mold 30 shown in FIG. The normal vector of the actual curved surface 310 when it is 300 is substantially matched. Thereby, the anti-reflective part which has an effect similar to the optical element 10 (refer FIG. 1) mentioned above can be shape-molded. In addition, the fine periodic uneven | corrugated | grooved part 31 of this Ni type | mold 30 is also 100-400 nm in the pitch of an uneven | corrugated | grooved part from a viewpoint of visible light reflection.

  In FIG. 3D, a glass mold 40 which is a lower mold is for forming the other lens surface and antireflection portion of the optical element (biconvex lens), and the Ni mold 30 described above is formed on the mold surface. And a plurality of fine periodic concavo-convex portions 43 which are the same as those in FIG.

  According to the Ni mold 30 and the glass mold 40 according to this embodiment as described above, the shape of the fine periodic concavo-convex portion 31 or 43 is transferred to the molding material, so that the antireflection portion having the uniform antireflection effect as described above is obtained. It is possible to manufacture an optical element having a large amount at a low cost.

  As described above, since the member having the antireflection portion according to the present invention is not limited to the optical element, the molding die according to the present invention can also be applied to members other than the optical element.

  Next, an embodiment of a method for manufacturing a mold according to the present invention will be described with reference to FIGS. First, the manufacturing method of the Ni mold 30 described above will be described with reference to FIGS.

  In FIG. 2A, reference numeral 200 denotes an Al (aluminum) substrate that serves as the mold 20 for forming the fine periodic concavo-convex portion 31 in the Ni mold 30. When anodizing is performed in an electrolytic bath using the Al base 200 as an anode (+ electrode), a large number of fine and periodic uneven portions 220a, as shown in FIG. A porous layer 220 made of 220b is formed.

  The center lines of the individual concavo-convex portions 220a and 220b substantially coincide with the normal vector of the curved surface 210 when it is assumed that the concavo-convex portions 220a and 220b do not exist (FIG. The individual concavo-convex portions 220 a and 220 b are oriented in the direction of approximately 90 ° with respect to the curved surface 210.

  Next, as shown in FIG. 2C, when the concave and convex portions 220a and 220b constituting the porous layer 220 of the Al base 200 are shaped into cone-shaped concave and convex portions 22a and 22b by wet or dry etching, a fine period is obtained. The mold 20 having the uneven portion 22 is completed.

  Thereafter, as shown in FIG. 2 (d), Ni is deposited and laminated on the fine periodic concavo-convex portion 22 of the above-described mold 20 by electroforming until a Ni base 300 to be the Ni mold 30 is obtained. Thereby, on the curved surface 310 of the Ni substrate 300, the fine periodic concavo-convex portion 31 having a shape obtained by accurately inverting the fine periodic concavo-convex portion 22 of the mold 20 is formed. Finally, the Ni mold 30 shown in FIG. 2E is completed by removing the mold 20 by Al dissolution treatment.

  Next, the manufacturing method of the glass mold 40 mentioned above is demonstrated, referring FIG. 3 (a)-(e). As described above, FIGS. 3A to 3E show the manufacturing process of the glass mold 40.

  In FIG. 3A, reference numeral 400 denotes a glass substrate that becomes the glass mold 40, and has a curved surface 410 that forms the base of the mold surface. First, as shown in FIG. 3B, an Al film 420 is formed on the curved surface 410 of the glass substrate 400 by physical vapor deposition such as sputtering or vacuum vapor deposition.

  Here, in this embodiment, the purity of aluminum forming the Al film 420 is 99% or more, and the surface roughness of the formed aluminum is about 50 nm or less. Thereby, the uniformity of each uneven part 43a, 43b of the fine periodic uneven part 43 formed by the anodizing process mentioned later can be aimed at.

  Further, when the Al film 420 is formed as shown in FIG. 3B, it is preferable to secure a film thickness of about 2 μm or more. If the film thickness of the Al film 420 is less than about 2 μm, all of the deposited aluminum is melted and the glass substrate 400 is exposed in an anodic oxidation process described later.

  Next, when anodizing is performed in an electrolytic bath using the glass substrate 400 on which the Al film 420 is formed as an anode, as shown in FIG. 3 (c), a plurality of fine and periodic concavo-convex portions 430a and 430b are formed. A porous layer 430 is formed.

  The center lines of the individual concavo-convex portions 430a and 430b substantially coincide with the normal vector of the curved surface 410 when the concavo-convex portions 430a and 430b are assumed not to exist ((c) in the enlarged view). The individual concavo-convex portions 430 a and 430 b are oriented in a direction of approximately 90 ° with respect to the curved surface 410.

  Thereafter, as shown in FIG. 3D, the concave and convex portions 430a and 430b constituting the porous layer 430 of the glass substrate 400 are wet or dry etched to form cone-shaped concave and convex portions 43a and 43b. Further, when the etching is continued in this state, a fine uneven shape is formed on the curved surface 410 of the glass substrate 400 as shown in FIG. Then, the remaining Al layer is removed by means such as melting, whereby the glass mold 40 having the fine periodic concavo-convex portions 43 is completed. Moreover, although not shown, the strength and durability of the mold can be improved by Ni-plating the fine periodic uneven portion 43 of the Al film 420.

  According to the method for manufacturing the Ni mold 30 and the glass mold 40 of the present embodiment, the surface of the mold base 200 or the curved surfaces 210 and 410 of the mold base 200 and 400 used for manufacturing the mold are finely processed by anodization. Since the periodic uneven portions 22 and 43 are formed, the individual uneven portions 22a and 22b or 43a and 43b constituting the fine periodic uneven portions 22 and 43 are directed in the direction of the normal vector of the curved surfaces 210 and 410. In particular, even when the curved surfaces 210 and 410 have a large area, the fine periodic uneven portions 22 and 43 can be formed at a uniform pitch.

  Next, a method for manufacturing an optical element using the Ni mold 30 and the glass mold 40 of the present embodiment described above will be described with reference to FIGS. 4 (a) and 4 (b) and FIGS. 5 (a) and 5 (b). To do. 4 (a) and 4 (b) are explanatory diagrams showing a resin material supply process to the Ni mold 30 and the glass mold 40, FIG. 5 (a) is a resin material curing process, and FIG. 5 (b) is a mold release process. It is explanatory drawing which shows.

  In FIG. 4 (a), the Ni mold 30 is arranged as the upper mold, the glass mold 40 is arranged as the lower mold, and the two molds 30 and 40 are moved relatively close to each other so that the fine periodic irregularities as shown in FIG. A cavity surrounded by the portions 31 and 43 is formed. And the ultraviolet curable resin 700 (refer FIG. 5A) is filled in the said cavity with the syringe 50 connected to the resin material supply apparatus which is not shown in figure.

  Next, as illustrated in FIG. 5A, the ultraviolet curable resin 700 in the cavity is cured by irradiating the ultraviolet rays with the ultraviolet irradiation device 60 through the glass mold 40. Thereafter, as shown in FIG. 5B, the Ni mold 30 and the glass mold 40 are released, and the optical element (biconvex lens) 70 as a molded product is taken out. The optical element 70 has antireflection portions 71 and 72 that are inverted shapes of the fine periodic concavo-convex portions 31 and 43 on the optical surface, and the individual concavo-convex portions that form the antireflection portions 71 and 72 are respectively It faces the normal direction of a virtual curved surface (not shown) that conceptually touches (see the enlarged view of FIG. 1).

  Here, since each uneven part of these anti-reflective parts 71 and 72 faces the normal line direction of a virtual curved surface (not shown), it is necessary to consider an undercut in the mold release in FIG. is there. Therefore, for example, the Ni mold 30 is divided into five divided molds 30A, 30B, 30C, 30D, and 30E as shown in FIG. 6, and the divided mold 30A is vertically arranged in the order of “1” to “5” attached to the drawing. After sliding in the direction, the molds 30B, 30C, 30D, and 30E are smoothly released by sliding in the normal direction of the virtual curved surface, which is the direction of the individual uneven portions of the antireflection portions 71 and 72. can do.

  Furthermore, as shown in FIGS. 7A to 7C, when the optical element 80 as a molded product is a concave lens, for example, the Ni mold 30 is divided into divided molds 30A and 30B as shown in FIG. , 30C, 30D, and 30E, and the divided mold 30A is slid vertically in the order of "1" to "5" attached to the drawing, and then the divided molds 30B, 30C, 30D, and 30E are reflected. By sliding in the normal direction of the virtual curved surface which is the direction of the individual concavo-convex portions of the prevention portion 81 (the arrow direction with the numbers “1” to “5” in FIGS. 5B and 5C) Can be released smoothly.

  6 and 7, it is essential to slide the split mold 30A first, but the split molds 30B, 30C, 30D, and 30E are all the same or “2” to “ It may be slid in an order different from “5”. Further, not only the Ni mold 30 but also the glass mold 40 is the same as described above. Moreover, when there is some undercut, it may be possible to release the mold vertically without dividing the mold.

It is a side view which shows the member (optical element) which has the reflection preventing part which concerns on one Embodiment of this invention. FIGS. 4A to 4E are explanatory views showing a manufacturing process of a Ni mold that is a mold (upper mold) according to the present embodiment. The same figure (a)-(e) is explanatory drawing which shows the manufacturing process of the glass type | mold which is a shaping | molding die (lower mold | type) which concerns on this embodiment. (A), (b) is an explanatory view showing a resin material supplying step to a mold in the method of manufacturing an optical element using the Ni mold and the glass mold. Similarly, the manufacturing method of the optical element using the said Ni type | mold and a glass type | mold is shown, The figure (a) is a hardening process of a resin material, The figure (b) is explanatory drawing which shows a mold release process. It is explanatory drawing which shows the order of the said Ni type | mold division | segmentation type | mold and its mold release. It is explanatory drawing which similarly shows the order of the said Ni type | mold division | segmentation type | mold and its mold release, The figure (a) is a top view, The figure (b) is the AA arrow directional view of the figure (a), the figure. Fig. (C) is a view taken along line BB in Fig. (A). It is a side view which shows the optical element which has the conventional antireflection part (SWS structure). It is a graph which shows the relationship between the light beam incident angle (theta) and the reflectance of the conventional antireflection part (SWS structure).

Explanation of symbols

10 Optical element (member having antireflection part)
11 Anti-reflective part (fine periodic uneven structure)
11a, 11b Uneven portion 12 Curved surface 20 Mold 22 Fine periodic uneven portion 22a, 22b Uneven portion 30 Ni type (molding die)
31 Fine periodic irregularities 40 Glass mold (molding mold)
43 fine period uneven part 43a, 43b uneven part 50 syringe 60 ultraviolet irradiation device 70 optical element (member having antireflection part)
71, 72 Anti-reflective part (fine periodic uneven structure)

Claims (15)

  Each of the antireflection portions having a fine periodic uneven structure formed at a pitch equal to or less than the wavelength of the light ray to be antireflective is formed on at least a part of the actual or virtual curved surface forming the member. A member having an antireflection portion, characterized in that a center line of the concavo-convex portion substantially coincides with a normal vector of the curved surface when it is assumed that the antireflection portion does not exist.   2. The member having an antireflection part according to claim 1, wherein the pitch of the concavo-convex parts forming the antireflection part is 100 to 400 nm.   3. The member having an antireflection portion according to claim 1, wherein the curved surface of the member is a spherical surface, an aspherical surface, or a free curved surface.   4. The member having an antireflection portion according to claim 1, wherein the member is an optical element.   A mold for producing a member having an antireflection part according to claim 1, 2, 3, or 4, wherein the antireflection part is inverted at least in part of a real or virtual curved surface forming a mold surface. And the center line of each of the irregularities forming the fine periodic irregularities is substantially matched with the normal vector of the curved surface when the fine periodic irregularities are not present. A mold characterized by that.   6. The mold according to claim 5, wherein a pitch of the uneven portions forming the fine periodic uneven portions is set to 100 to 400 nm.   7. The mold according to claim 5, wherein the curved surface forming the mold surface is a spherical surface, an aspherical surface, or a free curved surface.   8. The mold according to claim 5, 6 or 7, wherein the mold is used for manufacturing an optical element.   9. A method for producing a mold according to claim 5, 6, 7 or 8, wherein the fine periodic concavo-convex portion or the same is inverted on the curved surface of the mold or the mold for producing the mold. The manufacturing method of the shaping | molding die characterized by including the process of forming the fine periodic uneven | corrugated | grooved part by an anodizing process.   The method for producing a mold according to claim 9, further comprising a step of forming the fine periodic concavo-convex part or the fine periodic concavo-convex part obtained by inverting the fine periodic concavo-convex part by anodizing aluminum.   The method for producing a mold according to claim 10, wherein the purity of the aluminum is 99% or more.   The method for producing a mold according to claim 10 or 11, wherein the surface roughness of the aluminum is 50 nm or less.   13. The method for producing a molding die according to claim 10, 11 or 12, wherein the aluminum is formed into a film on the base to be the molding die or the mold and anodized.   14. The method for manufacturing a mold according to claim 13, wherein the film thickness of the aluminum film formed on the substrate serving as the mold or the mold is 2 μm or more. 15. The method for producing a mold according to claim 9, 10, 11, 12, 13, or 14, wherein the fine periodic irregularities formed by anodizing or the fine periodic irregularities obtained by inverting the fine periodic irregularities are plated with Ni. .

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